Magnetic-drive centrifugal pumps may be used to pump fluids, such as caustic and hazardous liquids. Instead of shaft seals, a magnetic-drive pump features a pump shaft separated from a drive shaft by a containment shell. The drive shaft is arranged to rotate with one magnetic assembly, which is magnetically coupled to another magnetic assembly. The magnetic assemblies cooperate to apply torque to the pump shaft or an impeller to pump a fluid contained by the containment shell.
Although many magnetic-drive centrifugal pumps are generally reliable, the containment shell may leak or burst from the presence of one or more of the following factors: exposure to excessive heat, exposure to excessive hydraulic pressure, exposure to extreme hydraulic transients, long-term exposure to caustic or corrosive fluids, lack of proper pump maintenance, exposure to excessive particulate matter, and exceeding other operating limitations of the pump. If the pumped fluid is caustic or corrosive, the pumped fluid may erode the interior of the containment shell such that the integrity of the containment shell is degraded over time. If the pump is not properly maintained, excessive radial bearing wear may lead to rubbing or scraping mechanical contact between the impeller and the containment shell that damages the fluid containing capacity of the containment shell. Further, if particles in the pumped fluid accumulate or lodge between the containment shell and the impeller, the containment shell may become scratched, eroded or pitted; and hence, more vulnerable to chemical attack from the pumped fluid.
Leakage of the pumped fluid from an improperly maintained, misused or abused pump may be associated with health and safety risks because the pumped fluid may be hazardous, caustic, flammable, or toxic, for instance. According, even if the probability of a leak of containment shell is relatively low, a need exists for a secondary containment scheme for containing the pumped fluid in the event the containment shell leaks or bursts for any reason.